The use of field-installed test ports is known in the prior art. For example, U.S. Pat. No. 4,411,459 to Ver Nooy discloses a branch fitting for accessing the interior of a pipe which may be used as a test port. Specialized tools or valve parts used to pierce or otherwise provide a tapping means of a closed air or fluid system are similarly disclosed in U.S. Pat. No. 5,301,532 to Bickmore et al. (Device for tube piercing and fluid irrigation); U.S. Pat. No. 4,955,406 to Antoniello (Connector device for water pipes); U.S. Pat. No. 4,752,387 to Thomas (Device and method for installing a by-pass filter); U.S. Pat. No. 4,620,576 to Owen, Jr. (Device and method for piercing a container); U.S. Pat. No. 4,537,214 to Cowan (Single seal pipeline tapping device with secure valve); U.S. Pat. No. 4,112,944 to Williams (Tube clamp and piercing device); U.S. Pat. No. 4,043,333 to Munsch (Clamp on injection site device); U.S. Pat. No. 3,999,785 to Blakeley (Mechanical pipe outlet device); and U.S. Pat. No. 3,981,322 to Gebelius (Pipe connecting device). Thus the basic concept of field-installed access to the interior environment of an existing pipe or duct system is known. Each of these prior art patents discloses apparatus designed to tap into an existing pipe or duct system. Each apparatus fulfills its respective particular objectives and requirements and is most likely quite functional for its intended purposes. It will be noticed that none of the prior art cited discloses an apparatus that allows a user to efficiently and inexpensively install a corrosion-resistant test port in an existing exhaust air transfer ductwork system which is designed to handle a wide range of corrosive exhaust streams which may be found in a wide variety of industrial applications. There apparently still exists the need for new and improved test ports and installation kit apparatus operable with an existing exhaust air transfer system that is designed to handle a wide range of corrosive exhaust streams without having to customize a test port or otherwise custom cut the duct carrying the gas stream to be monitored. The present invention substantially fulfills this need.